TWI398987B - Wireless IC tag - Google Patents

Description

Wireless IC tag

The present invention relates to a technique of a wireless IC (integrated circuit) tag, and more particularly to a technique related to impedance matching of a micro stripe antenna mounted on a wireless IC tag.

The wireless IC tag can wirelessly transmit and receive information such as an ID number stored in the wireless IC tag. Therefore, the information memorized by the wireless IC tag can be read contactlessly by communication between the reader/writer and the wireless IC tag. Because wireless is used, information on the IC chip can be read even when placed in a bag or box. Therefore, it is widely used in manufacturing management or logistics management of articles.

Such a wireless IC tag is composed of an IC chip on which information is recorded, and an antenna that wirelessly transmits and receives information recorded on the IC chip. There are various types of antennas for antennas used in wireless IC tags. A representative example thereof is a dipole antenna in which the terminals of the IC chip are respectively connected to the ends of the two metal pieces. Because of its simple structure, the dipole antenna is also cheaper in product price and suitable for a large number of stickers. However, when the material of the article in which the wireless IC tag is attached is made of metal, or a substance containing water such as trees, meat, raw materials, or wild vegetables, the communication distance is remarkably lowered and there is a possibility that communication cannot be performed. An antenna in which a wireless IC tag is attached to such an item to ensure a stable communication distance is generally known as a microstrip antenna.

A general microstrip antenna is configured by sandwiching a dielectric body between two conductors such as a radiation electrode and a ground conductor. The power supply to the antenna is operated by connecting the radiation electrode to the ground conductor. When a microstrip antenna is used for a wireless IC tag, the two terminals of the mounted IC chip are connected to the power supply point of the antenna.

However, since the microstrip antenna is connected between the conductors through the terminals of the IC chip through the dielectric body, when the antenna is deformed by an external force, the distance between the antennas may change, and the connection may be broken.

The impedance matching between the IC chip and the antenna will be described below.

The impedance of the IC chip consists of a resistive component and a reactance component. The impedance of the antenna is also composed of a resistive component and a reactive component. For example, the reactance component of the IC chip and the capacitance component, when the reactance component of the antenna is equivalent to the inductance component, can offset the respective effects, so that the current generated by the antenna can effectively flow into the IC chip to operate. However, when the connection between the antenna and the antenna is caused by the variation (error) of the capacitance component and the reactance component, that is, the impedance mismatch, the current generated by the antenna cannot be efficiently supplied to the IC chip, and it becomes a wireless IC tag. The reason for the reduced communication distance. As such a technique of impedance matching, there is known a technique of changing the power supply position of an antenna, performing impedance matching of an antenna, or performing impedance matching of an antenna by connecting a coil or a capacitor to an antenna, or borrowing a power supply portion of a processing antenna. A technique of impedance matching of an antenna is performed by a configuration called a slit (Patent Document 1).

Patent Document 1: JP-A-2002-135029

As described above, the microstrip antenna is less susceptible to the material of the IC tag mounting object, and the IC chip can be mounted on the radiation electrode to improve the resistance to external force of the IC chip.

However, in the impedance matching type slit disclosed in Patent Document 1, the impedance matching range that can be obtained is narrow, and when the impedance difference between the IC chip and the antenna becomes large, impedance matching may not be obtained in the gap. In addition, when the size of the wireless IC tag is limited, the size (size) of the antenna is smaller than the frequency used, that is, the tuning frequency of the antenna, and the capacity component of the IC chip and the impedance between the IC chip and the antenna cannot be cancelled. Become a mismatched state. To get closer to the impedance match, you need to correct the shape of the antenna.

In addition, the impedance of the feeding point of the radiation electrode also changes when the thickness of the dielectric body of the microstrip antenna changes. That is, when the thickness of the label changes, it is necessary to adjust the impedance matching between the IC wafer and the radiation electrode in a timely manner.

Further, in the method of obtaining impedance matching by the coil, the use of the coil inevitably increases the overall size of the label, and is not suitable for miniaturization of the label.

The present invention has been made in view of the above problems, and an object of the invention is to provide a microstrip antenna for a wireless IC tag, which can obtain impedance matching with an IC chip without changing the shape of the antenna even in a small microstrip antenna.

In the present invention, among the two conductors constituting the microstrip antenna, the radiation electrode of one of the conductors is composed of a first radiation electrode having an IC chip and a slit, and a U-shaped second radiation electrode; : an opening formed by the first radiation electrode and the second radiation electrode, a notch portion, and a radiation electrode.

(summary of each embodiment)

Preferred embodiments of the wireless IC tag according to the best mode of the present invention (hereinafter referred to as the present embodiment) will be described below with reference to the drawings. In the following description of the embodiments, the value indicating the impedance matching state is represented by a return loss as an index. The foldback loss is expressed as the ratio of the injected power to the reflected power in the feed point of the antenna, and is 0 dB when the total power is fully reflected and the power is folded back. When all power is not folded back, it is -∞dB.

A typical microstrip antenna is composed of a radiation electrode that emits radio waves, a dielectric body, and a ground conductor, and is called a patch antenna. The resonant frequency of the antenna is determined by the size of the radiation electrode. Further, the impedance matching of the bulk antenna of the microstrip antenna can be performed by connecting the center of the radiation electrode to the ground conductor and changing the distance from the center point to the position of the feed point. Figure 10 shows the foldback loss characteristics of the block antenna when simulating the position of the mobile feed point. The vertical axis represents the foldback loss, and the horizontal axis represents the frequency distribution. In this way, even if the distance from the center point of the radiation electrode to the position of the feeding point is changed, the resonance frequency of the antenna hardly changes, and only the foldback loss changes. Therefore, it can be confirmed that the impedance of the antenna is changed by moving the feeding point. As described above, the resonance frequency is related to the size of the radiation electrode, and when the conventional microstrip antenna is used as the antenna of the wireless IC tag, the size of the radiation electrode cannot be arbitrarily changed.

Fig. 11 shows the opening loss characteristics of the second impedance matching portion in the following embodiments, and the value of the L3 is changed in a 10-stage manner. The frequency of the minimum point of the foldback loss is expressed by 10 points according to the distribution. Here, it is shown that the tuning frequency of the antenna can be changed by changing the size of the opening formed by the first radiation electrode and the second radiation electrode, and the reactance component in the feeding point can be largely controlled by the size of the opening. In this way, a wide range of impedance matching can be performed without changing the outer dimensions of the antenna to solve the problem of the present invention.

As described above, in the following embodiments, the size of the opening formed by the first radiation electrode and the second radiation electrode can be greatly changed without changing the antenna size of the microstrip antenna, and the antenna component can be greatly expanded. The impedance matching range in the power supply point makes it easier to obtain the impedance matching between the radiation electrode and the IC chip.

(First embodiment)

Fig. 1 is a view showing a radiation electrode portion of the embodiment. The first radiation electrode 1 is a first impedance matching unit, and has an L-shaped slit 3 formed by a notch portion on one side of the antenna, and a rectangular opening 4 formed by the U-shaped second radiation electrode and the first radiation electrode 1 This is the second impedance matching unit. The notch portion 5 formed by the first radiation electrode and the second radiation electrode is a third impedance matching portion, and the IC wafer 6 is attached to the first impedance matching portion 3.

However, the shape of the opening 4 formed in the radiation electrode is not limited to a rectangular shape, and for example, a circular shape may function as an impedance matching portion.

FIG. 2 shows a method of connecting the IC chip 1 and the first impedance matching unit. Fig. 2(a) shows a first impedance matching portion of the radiation electrode 1a, and shows an L-shaped slit 3a. 2(b) shows two output terminals 6a, 6b of the IC chip 6. The output terminals 6a and 6b are formed in the form of bumps made of Au on the surface of the IC wafer 6. Fig. 2(c) shows a state in which the IC wafer 6 is mounted on the first radiation electrode 1a. The output terminals 6a, 6b of the IC chip 6 are connected across the open ends of the slit 3a. The L-shaped slit 3a can be configured to perform the same operation even if it is a T-shaped slit.

Fig. 2 (d) is a cross-sectional view showing a state in which the IC wafer 6 is mounted on the first radiation electrode 1a. The bumps of the radiation electrode and the IC wafer 6 are electrically connected by ultrasonic bonding or metal eutectic bonding, or by using a conductive adhesive or the like. The first radiation electrode 1a may have a conductive material, and a metal foil such as Al, Au, Ag, or Cu or a vapor deposited film or a conductive paste is usually used. In the present embodiment, a 20 μ thick Al foil was used, and the connection to the IC wafer was performed by ultrasonic bonding.

Fig. 3 shows the structure of a microstrip antenna in which the first radiation electrode 1 and the second radiation electrode 2 are integrated in the present embodiment. 3(a) shows the configuration of each layer, and includes the radiation electrode 7 with the IC wafer 6 as an upper layer, and the radiation electrode 7 has a slit 3 of the first impedance matching portion, an opening 4 of the second impedance matching portion, and a third impedance matching. The notch portion 5 of the portion; the structure of the dielectric body 8 and the back surface conductor 9 are disposed in the lower layer. The dielectric body 8 was made of 300 μm thick PET (Polyethylene Terephthalate), and the back surface conductor 9 was made of a 1 mm thick Al plate. Fig. 3(b) shows the appearance of each layer. Among them, the back surface conductor 9 indicates a conductor in which the IC wafer is not mounted among the two conductors constituting the microstrip antenna.

The matching method of the impedance matching unit will be described below. 4(a) shows the length L and the width W of the radiation electrode 7 in which the first radiation electrode 1 and the second radiation electrode 2 are integrated, and the width L2 of the portion corresponding to the first radiation electrode 1, and the length L3 of the opening, respectively. The length L4 of the upper opening of the radiation electrode 1 and the second radiation electrode 2, the width W of the radiation electrode 1, the width W1 of the opening on the left side of the second radiation electrode, and the length W2 of the first radiation electrode 1, and the second The width W3 of the right side of the opening of the radiation electrode 2 and the slit length SL of the L-shaped longitudinal direction of the first impedance matching portion formed in the first radiation electrode.

Figure 4(b) shows the direction of current flow on the radiation electrode. The current flowing through the second radiation electrode is roughly indicated by the flow 21 of the current on the second radiation electrode and the flow 20 of the current on the first radiation electrode. Further, when the length of the flow of the current on the second radiation electrode is regarded as a circuit having a specific width, the radiation electrode formed around the opening is a path in which the center position of the specific width is continuously connected, and the equivalent is reduced. The value after the length 21 of the region of the first radiation electrode in which the slit is formed. Here, in the case where the wavelength of the radio wave to be used is λ, the length is a length corresponding to λ/2, and the corresponding frequency becomes a resonance frequency.

When the length of λ/2 is set to Lfc, it can be expressed as Lfc=1/2(W1+W3)+W2+(1/2(L2+L4)+L3)×2

Therefore, Lfc can be controlled by the length of the two sides of the opening, that is, the lengths of L3 and W2, and the lengths of the two sides of the notch, that is, L1 and W2.

Hereinafter, an example in which the size of the radiation electrode 7 is set to L=25 mm and W=35 mm is described. First, when L and W are set to a fixed value, as in the conventional structure, only the first impedance matching portion is provided, and in the state where the opening 4 is formed by the first radiation electrode and the second radiation electrode, impedance matching cannot be obtained. It is impossible to communicate with the IC chip 6.

Fig. 11 shows an antenna characteristic in which the length W2 of the first radiation electrode is set to 10 mm, W1 = W2 = W3, L1 = 0 mm, L2 = 2 mm, and the length of L4 is changed within 1 to 12 mm in units of 1 mm by analog. L1 and L2 are fixed values, so the change in L4 corresponds to the change in L3. The resonance point corresponding to the length of L4 is shown, and the smaller the length of L4, the lower the resonance frequency becomes. Since L3 = L - (L1 + L2 + L4), it can be confirmed that the length of the opening side L3 becomes longer, and the resonance frequency becomes lower. As a result of the simulation, it is set that the length of W2 is 10 mm and the change is L3. Therefore, the phenomenon that the resonance frequency becomes low means that the opening circumference tends to be long. That is, it means that the resonance frequency becomes lower as the circumference becomes longer. Among them, the low resonance frequency indicates that the electrical length of the antenna extends, which means that the reactance component of the antenna increases. As described above, it is known that the effect of increasing the reactance component of the antenna can be achieved by increasing the circumference of the opening formed by the first radiation electrode and the second radiation electrode.

The specific length of L3 is calculated below. In the present embodiment, it is assumed that communication is performed at 2.4 GHz, and thus the length of L3 of the 2.4 GHz resonance is calculated. The simulation results, L4 = 4 mm, that is, L3 = 9 mm. Fig. 13 shows the relationship between the length of L4 and the resonance frequency when L4 is a variable. In addition, in this case, the foldback loss is 22 dB. In addition, the impedance adjustment with higher accuracy can be performed by the first impedance matching unit. Fig. 12 shows an antenna characteristic when L3 = 9 mm is set and the length of the slit 3 is SL = 2 to 6 mm as a variable. In this case, the fold loss is changed from -3 to 24 dB. In the case of this example, the fold loss at SL=4mm can be changed from -22dB to -24dB, and up by 2dB.

The method of changing the length of the opening side L3 is the width L2 of the first radiation electrode. Fig. 14 is also a view showing the relationship between the length of L2 and the resonance frequency when L2 is a variable. When the L2=2 to 13 mm resonance frequency changes from 1.9 to 3.3 GHz, it can correspond to the desired frequency without changing the outer dimensions of the radiation electrode.

Further, the effect of the third impedance matching unit, that is, the notch portion 3 will be described. When the length L1 of the notch portion 3 formed by the first radiation electrode 1 and the second radiation electrode 2 is changed, the resonance frequency changes. Set L2 = 2mm, L4 = 2mm fixed value, change L1. Figure 16 is a graph showing the relationship between the length of L1 and the resonance frequency. When the L1 is 0 to 8 mm, the change in the resonance frequency is 3.3 to 1.9 GHz. When L1 is increased, that is, when the notch is increased, the resonance frequency is increased. This means that by increasing L1, L3 will become smaller and the opening will become smaller.

As a result of measuring the communication distance of the antenna having a dielectric thickness of 300 μm as described above, a communication distance of 60 mm was obtained in a reading device having a frequency of 2.45 GHz, a transmission output of 200 mW, and an antenna gain of 6 dBi. Fig. 15 shows the result of measuring the communication distance with the length of L3 as a variable. When L3 = 8 mm, the maximum communication distance of 60 mm can be obtained, and when L3 = 5 mm or less and 11 mm or more, communication with the IC chip cannot be performed.

The reason why two of the first impedance matching unit and the second impedance matching unit are used will be described below. As described above, the second impedance matching unit is characterized in that the impedance can be largely adjusted in comparison with the first impedance matching unit. In other words, the second impedance matching unit performs coarse adjustment of the impedance, and the first impedance matching unit performs fine adjustment of the impedance.

When the radiation electrode is formed only by the second impedance matching portion, the structure is a loop shape. When the shape of the radiation electrode is small, it becomes a thin loop shape. In the case of a microstrip antenna, the larger the area of the radiation electrode, the larger the amount of the magnetic field vibrating on the surface of the radiation electrode, and the stronger electric field can be emitted. Therefore, the microstrip antenna having the first impedance matching unit and the second impedance matching unit of the present embodiment can realize a more efficient antenna and can provide communication as compared with an antenna having no circuit shape of the first impedance matching unit. A longer wireless IC tag.

(Second embodiment)

Fig. 5 is a view showing a structure of a label of a second embodiment; In the second embodiment, a method in which the small lead-in line 10 is used as the first radiation electrode and the second radiation electrode 2a is combined to realize the wireless IC tag of the present embodiment. The small-sized lead-in wire 10 shown in Fig. 5 (b) is a 20 mm long side of the lead-in wire (50 mm long) for the wireless IC tag used for the 2.4 GHz band. The lead-in means that the IC chip is mounted on the antenna. In the present embodiment, the lead-in line in which the IC chip is mounted on the dipole antenna is used. In the lead-in line, an L-shaped slit 3b is formed for impedance matching with the IC wafer 6, which is the first impedance adjusting portion in the present embodiment. In addition, a lead-in member (dielectric member) made of a synthetic resin material such as PET (polyethylene), PP (polypropylene terephthalate), or PE (polyethylene) may be used as a lead-in wire for packaging an antenna and an IC wafer.

The second radiation electrode 2a is formed by adding an aluminum foil having a thickness of 20 μm. The outer dimensions L and W are the same as in the first embodiment.

As shown in FIG. 5(c), the small lead-in wire 10 and the second radiation electrode 2a are disposed at positions overlapping each other, and thus the power supply portion of the IC chip is separated from the other radiation portions. The opening 4a of the radiation lead surface formed by the small lead-in wire 10 and the second radiation electrode 2a is the second impedance adjusting portion of the present embodiment. Fig. 5(d) is a cross-sectional view taken along line A-A' of Fig. 5(c). In this manufacturing method, the small lead-in wire 10 is placed on the substrate 8a, and the second radiation electrode 2a is laminated thereon to be manufactured.

The substrate 8a is used as a dielectric body having a microstrip structure, and a back conductor is disposed on the back surface thereof to form a microstrip antenna.

In addition, the arrangement of the small lead-in wire 10 and the second radiation electrode may be electrically connected to each other, and may be a direct current connection, or a distance that can be electrostatically coupled by a laminated member or a bonding material of a small lead-in wire by an alternating current. Therefore, the small lead-in wire 10 can also be disposed on the second radiation electrode.

Further, when the antenna of the lead-in wire and the second radiation electrode 1d are coupled via a dielectric body, the influence of the dielectric body lengthens the electrical length of the antenna. That is, the reactance component can be further increased, and thus the effect of increasing the range of the impedance adjustment range is obtained.

A resin substrate (not shown) such as PET or PP may be attached to the upper layer of the second radiation electrode 1d as a protective layer material such as an antenna. The base material 8a can be integrally formed by a heat sealing method using a PET, PP, or PE synthetic resin substrate.

The wireless IC tag manufactured in the present configuration can also obtain the same communication characteristics as the wireless IC tag manufactured in the first embodiment.

(Third embodiment)

Fig. 6 shows a method of continuously manufacturing the label structure of the second embodiment in the embodiment. In the second embodiment, the inlet 10 of the first radiation electrode 1 and the second radiation electrode of the U-shaped metal foil are superposed on each other. When manufacturing a single body, it takes a lot of time to superimpose the first radiation electrode and the second radiation electrode. In order to solve this problem, the first radiation electrode sheet 144 and the second radiation electrode sheet 141 in which the first radiation electrode and the second radiation electrode are formed on a sheet are stacked and continuously manufactured. Fig. 6(a) shows the form of the second radiation electrode sheet 141. A mark 143 for alignment with the opening 142 is formed in the second radiation electrode sheet 141. As the material, a metal foil having a conductivity of 20 μm such as Al or Cu is used. Further, although not shown, a resin film such as PET, PP, or PE for reinforcing one side or two-layer layers of the metal foil may be used. The second radiation electrode may be formed by printing a conductive paste on a resin film or a paper material. Fig. 6(b) shows the form of the first radiation electrode sheet 144. A mark is continuously disposed on the resin substrate for calibration with the first radiation electrode 145 on which the gap for impedance matching is formed. The IC wafer 146 is mounted across the gap. An engineering schematic diagram in which the first radiation electrode sheet 144, the second radiation electrode sheet 141, and the protective film 147 are laminated is shown in Fig. 6(c). The first radiation electrode sheet 144 and the second radiation electrode sheet 141 detect the individual alignment marks 143 and the alignment marks 148 so that the portion corresponding to L3 of the opening 142 has a desired length, and thus the first radiation electrode 145 is positioned. The three overlapping films are individually fixed by heat sealing using a heater or by applying an adhesive.

FIG. 7(a) shows a state in which the first radiation electrode sheet 144 and the second radiation electrode sheet 141 are disposed and fixed at a desired position. These integrated radiation electrodes are cut by the cutting line 149 and the cutting line 150, and a desired radiation electrode equipped with an IC wafer can be obtained. Further, in order to simplify the work, the cutting position can be set to one of the cutting lines 149. Fig. 7(b) shows the cross-sectional shape of B-B' of Fig. 7(a). The figure shows a form in which the second radiation electrode 141 is laminated on the first radiation electrode 145, and a protective film 147 is laminated thereon. Contrary to this figure, the structure in which the first radiation electrode is disposed on the second radiation electrode performs the same operation.

(Fourth embodiment)

Fig. 8 is a view showing the structure of a tag according to a fourth embodiment of the wireless IC tag. Conventionally, a microstrip antenna is used in such a manner that a radiation electrode faces upward and is directed toward a radio wave. In the present embodiment, the radiation electrode and the back surface conductor are substantially the same size, and radio waves are emitted from the surface of the back surface conductor.

The wireless IC tag is required to be highly miniaturized, and it is also required to be highly thinned, so that the thinning of the IC chip itself is performed. On the other hand, the problem is that the thinning causes the IC chip to be destroyed by external pressure. In the microstrip antenna, a metal back surface conductor is disposed on the back surface of the antenna. The metal plate is used as an IC wafer reinforcing plate.

Fig. 8(a) is an external view of the plate-like label, and is a form in which the metal plate 53, the dielectric body 52, the radiation electrode 51, and the protective member 55 are sequentially laminated from the upper layer. In addition, there is a hole 54 to be adhered as a plate. The metal plate 53 has a structure corresponding to the back surface conductor of the microstrip antenna. As described above, the metal plate 53 and the radiation electrode 51 are set to have substantially the same size. Specifically, the inner side of 1 mm of the metal plate 53 is the size of the radiation electrode. This is to select a material that can be thermally welded by the dielectric body and the protective member to seal the IC chip and the radiation electrode, thereby improving the environmental resistance of the wireless IC tag. In addition, the identification information can be imprinted on the metal plate 53, and two kinds of information confirmation methods by visual communication and wireless communication can be provided.

In the present embodiment, the metal plate 53 is a stainless steel plate having a thickness of 1.2 mm, the dielectric body 52 is a laminated film of PET/PP (thickness of 300 μm), the radiation electrode 51 is an aluminum foil having a thickness of 20 μm, and the protective member 55 is a laminate of PET/PP. Film (600 μm thickness). The metal plate 53 and the dielectric body 52 are integrated by heat sealing by the dielectric member 52, the radiation electrode 51, and the protective member by the adhesive member.

The elliptical shape with a size of 30×20 (mm), a frequency of 2.4 GHz, a transmission output of 200 mW, and an antenna gain of 6 dBi can obtain a communication distance of 70 mm from the metal plate surface. When the metal plate 53 is used as a surface, the pressure resistance performance can be improved, and the strength of the surface thickness load of 10t and the point pressure load of 3t can be maintained. Fig. 8(b) is a sectional structural view thereof.

Fig. 9 is an illustration of an embodiment of a boundary pillar applied to concrete. Fig. 9(a) shows a form in which a wireless IC tag having the metal plate 53 as an upper surface is attached to the upper portion of the pile 56 made of concrete. The wireless IC tag is constructed as described above.

Fig. 9(b) shows the cross-sectional structure of A-A' of Fig. 9(a). The conventional technique is to cover the surface of the wireless IC tag with a resin cover portion (protective member) that does not block the radio wave. However, ultraviolet light irradiation of the sun causes deterioration of the resin and cannot be used for a long period of time. Among them, the resin member is not exposed to ultraviolet rays, and therefore has a feature that it can be used for a long period of time.

(effect of the invention)

According to the present invention, the microstrip antenna can be impedance matched to a desired frequency by the opening formed on the radiation electrode of the microstrip antenna without changing the antenna size of the microstrip antenna.

1, 1a, 1b. . . First radiation electrode

2, 2a. . . Second radiation electrode

3, 3a. . . First impedance matching unit (gap)

4, 4a. . . Second impedance matching unit (opening)

5. . . Second impedance matching unit (notch)

6. . . IC chip

6a, 6b. . . Bump

7. . . Radiation electrode

8, 8a. . . Dielectric body

9, 9a. . . Back conductor

10. . . Lead-in

20. . . Current on the first radiation electrode

21‧‧‧ Current on the second radiation electrode

51‧‧‧radiation electrode

52‧‧‧ dielectric

53‧‧‧Metal plate (back conductor)

54‧‧‧Opening

55‧‧‧Protection components

56‧‧‧Concrete piles

141‧‧‧2nd radiation electrode sheet

142‧‧‧ openings

143‧‧‧ calibration mark

144‧‧‧1st radiation electrode sheet

145‧‧‧1st radiation electrode

146‧‧‧ IC chip

147‧‧‧Protective film

148‧‧‧ calibration mark

149, 150‧‧‧ cut position

Fig. 1 is a view showing the configuration of a radiation electrode of the present invention.

Fig. 2 is a view showing the shape of the slit of the first embodiment.

Fig. 3 is a view showing the shape of the microstrip antenna of the first embodiment.

Fig. 4 is a view showing the shape of the radiation electrode of the first embodiment.

Fig. 5 is a view showing the shape of a radiation electrode of a second embodiment.

Fig. 6 is a view showing a method of manufacturing a radiation electrode according to a third embodiment;

Fig. 7 is a view showing the structure of a radiation electrode of a third embodiment.

Fig. 8 is a view showing the structure of a plate-like label of a fourth embodiment;

Fig. 9 is a view showing the shape of a boundary pile in the third embodiment.

Figure 10 is a graph showing the fold loss characteristics in a conventional microstrip antenna.

Fig. 11 is a graph showing the fold loss characteristic in the microstrip antenna of the first embodiment.

Fig. 12 is a graph showing the fold loss characteristic in the microstrip antenna when the slit length is changed in the first embodiment.

Fig. 13 is a view showing the relationship between the length of L4 and the resonance frequency in the first embodiment.

Fig. 14 is a view showing the relationship between the length of L2 and the resonance frequency in the first embodiment.

Fig. 15 is a view showing the relationship between the length of L3 and the communication distance in the first embodiment;

Fig. 16 is a view showing the relationship between the length of L1 and the resonance frequency in the first embodiment.

1. . . First radiation electrode

2. . . Second radiation electrode

3. . . First impedance matching unit (gap)

4. . . Second impedance matching unit (opening)

5. . . Second impedance matching unit (notch)

Claims (9)

A wireless IC tag comprising: an IC chip; a first conductor connected to the IC chip; a second conductor; a dielectric body formed between the first conductor and the second conductor; and a gap The two terminals of the IC chip formed on the first conductor are spanned, one end of the first conductor has an open portion, and the opening is surrounded by the first conductor. The length of the opening perimeter is positively correlated with the value of the impedance of the IC wafer minus the impedance of the first conductor; the notch portion is disposed on the first conductor, and the slit is disposed to face the opening. The wireless IC tag according to the first aspect of the invention, wherein the opening is a path in which a loop formed in a loop shape around the opening is formed by continuously connecting a center of a width of the loop The opening formed by subtracting the length of the half wavelength of the wavelength used to form the value of the edge having the slit. The wireless IC tag according to claim 2, wherein the first conductor is composed of a first radiation electrode having a power supply portion and a second radiation electrode of another portion, and the first radiation electrode and the second radiation The electrodes are connected via a second dielectric. The wireless IC tag of claim 3, wherein the opening and the notch are formed in the first radiation electrode and the second radiation electrode. The wireless IC tag of claim 3, wherein the first radiation electrode is an antenna of an inlet. The wireless IC tag of claim 5, wherein the second dielectric body is a substrate for holding a base film or a bonding material or a second radiation electrode of the inlet. The wireless IC tag according to any one of claims 1 to 5, wherein the first conductor and the second conductor are substantially the same size. A wireless IC tag having an IC chip and a microstrip antenna, wherein the microstrip antenna includes a radiation electrode having two impedance adjusting portions for adjusting the IC chip and the microstrip An impedance of the antenna; a conductor; and a dielectric body formed between the radiation electrode and the conductor; and the first impedance adjustment portion is a slit-shaped cutout portion; and the second impedance adjustment portion is electrically conductive around An opening surrounded by the body and a notch portion that is cut into the outer periphery of the first conductor with respect to the opening. The wireless IC tag of claim 8, wherein the opening is an opening formed in such a manner that when a radiation electrode formed around the opening is regarded as one loop, the center of the loop The value obtained by subtracting the length of the center line of the region corresponding to the first radiation electrode in which the slit is formed is the length of the half wavelength of the wavelength used.